For various reasons, I would like to run my S3s without internal drives. With the THD, this is easy: one merely swaps the SATA jumpers inside the TiVo so the primary drive is external to the TiVo and the secondary drive is internal. With the S3, it isn't quite so easy, however, since the secondary drive connector is a bulkhead connector on the motherboard facing the outside of the TiVo, rather than a SATA jumper cable. Depending on the BIOS and possibly the kernel, it might be possible, however, to boot the S3 with only an external drive. Presumably if the TiVo behaves like an ordinary PC in this respect, then in the absence of a drive on the primary controller, the drive on the secondary controller would be assigned /dev/hda, and I would think it would work. Looking at the device map, however, it appears to me hot-plugging is not enabled on the TiVo, so it may not assign the drives dynamically, either, in which case it won't work.

By chance has anyone attempted this? Does anyone much more familiar with the mechanics of the TiVo than I have any comments?

ciper

04-19-2009, 04:06 PM

Why not copy what the THD has,,, get an ESATA header and attach it to the internal port of the S3 and drill a hole in the back case where it can sit.

lrhorer

04-19-2009, 05:54 PM

I thought of this, of course, but I no longer have access to a wide variety of machine tools, and since the hole for the e-SATA port is not round, it can't be drilled. It has to be cut. What's more, for safety one should dis-mount the motherboard, fan, and power supply while performing the task. All in all, it's quite a bit of work when compared to simply plugging in an external drive, if it will work.

ronnythunder

04-20-2009, 12:47 AM

I thought of this, of course, but I no longer have access to a wide variety of machine tools, and since the hole for the e-SATA port is not round, it can't be drilled. It has to be cut. a cheap nibbler would probably work. i used this to put ethernet keystone jacks in my s1 boxes; just find a place close to the top of the back panel and start nibbling down. mounting might be tricky, but i bet you could come up with something.

having said that, perhaps a top-off test is in order to determine whether it works before committing. :)

ronny

lrhorer

04-20-2009, 12:55 AM

Well, there's no question routing the internal connector to an eSATA bracket installed in the back of the case would work. Plugging a single drive into the external connector would be much easier, however, if the TiVo can boot from the secondary SATA port. If, much like a desktop PC, the BIOS can boot from a drive on the secondary controller, and if, much like most kernel implementations, a solitary drive is assigned as the first hard drive target (hda) by the TiVo kernel, then it should work without modifying anything. If and if. Right now I have a dual drive setup, and I don't want to go to all the trouble to convert to a single drive and modify the case if it would all be for naught.

ciper

04-20-2009, 02:23 AM

Wouldn't you have to modify the kernel to make that assignment? I thought the device configuration was mapped to the specific "IDE" channel. I don't remember HDA/SDA being assigned automatically to the first drive in the PC world.

The an ESATA cable is pretty small. What if you made a hole in the case that passed the cable through and left the header inside of the case? There is plenty of room to make a hole between the power supply and motherboard.
http://www.gizmolovers.com/Photos/Series3-Review/Small/Inside-1.jpg

Jamie

04-20-2009, 08:29 AM

There is no need to patch the kernel. It's easy enough to reverse the device inodes /dev/hda and /dev/hdb. The question is, can the prom boot from the esata port?

lrhorer

04-21-2009, 12:32 AM

Wouldn't you have to modify the kernel to make that assignment? I thought the device configuration was mapped to the specific "IDE" channel. I don't remember HDA/SDA being assigned automatically to the first drive in the PC world.
It depends on the implementation. Hot-plugged devices are generally assigned their inode in the order of being presented to the system. On my hacking platform, for example, if I plug in the TiVo drive in its external housing and power it up prior to booting, then the boot drive winds up as /dev/sda, the TiVo as /dev/sdb, and the data drive as /dev/sdc. If I boot the system first and then attach the TiVo drive, the data drive is assigned /dev/sdb and the TiVo gets /dev/sdg. It does look to me like the TiVo may assign the drives statically, but as Jamie responds, it's not terribly difficult to swap the inodes.

The an ESATA cable is pretty small. What if you made a hole in the case that passed the cable through and left the header inside of the case? There is plenty of room to make a hole between the power supply and motherboard.
Well, if I'm going to go to the trouble of drilling the case, then I'm going to go ahead and cut a proper bulkhead entry and mount an eSATA bracket. Indeed, if I go to that trouble, I'll probably mount a pair of eSATA brackets, allowing me to swap the drives, rather than just run a single drive. I'm not fearful of modding the case, but it is a significant consideration.

ciper

04-21-2009, 12:58 AM

The implementation brings up a possible important difference between the THD and S3. The S3 actually has two separate SATA channels where as the THD is a single channel with a port multiplier. Somewhere on one of the forums I was talking about this. I eventually got in contact with an engineer at silicon image who sent me the data sheets for the SATA port splitter the THD has. According to the specifications it should be possible to have MANY more than just two drives and I can't see why the TiVo OS wouldn't support them. You could "easily" remove four jumpers on the board to disable the port splitter and put a sata head in its place giving you direct access to the CPU! But I am getting off track.

I am guessing the two units (THD and S3) are vastly different because of the SATA implementation so it might be up to the DDB members who specifically have an S3 to figure this out.

I'll probably mount a pair of eSATA brackets, allowing me to swap the drives, rather than just run a single drive. I'm not fearful of modding the case, but it is a significant consideration.
Thats a nifty idea! It would be a perfect TiVo test bench setup too. I bet your internal temps would go down. Not only would the drives heat be removed but the PS should produce more heat since it has less draw. The fan might not need to run at anything above the lowest speed.

lrhorer

07-13-2009, 08:36 PM

The implementation brings up a possible important difference between the THD and S3. The S3 actually has two separate SATA channels where as the THD is a single channel with a port multiplier. Somewhere on one of the forums I was talking about this. I eventually got in contact with an engineer at silicon image who sent me the data sheets for the SATA port splitter the THD has. According to the specifications it should be possible to have MANY more than just two drives and I can't see why the TiVo OS wouldn't support them. You could "easily" remove four jumpers on the board to disable the port splitter and put a sata head in its place giving you direct access to the CPU! But I am getting off track.
Interesting. Very.

Thats a nifty idea! It would be a perfect TiVo test bench setup too. I bet your internal temps would go down. Not only would the drives heat be removed but the PS should produce more heat since it has less draw. The fan might not need to run at anything above the lowest speed.
It is a neat idea, but I can't take credit for it. I do use it on 2 of my 3 TiVos. Here's the result of my mod on the S3:

http://fletchergeek.com/images/eSATA_S3.jpg

I just bought a $12 dual eSATA PCI bracket from my local electronics store, and then used a Dremel tool to cut off the bracket hold-down so I could use the bracket as a template. I removed the eSATA adapters, marked out the holes with an awl, and used the Dremel to cut the holes in the S3. I drilled out the mounting holes with a hand drill, and mounted the eSATA adapters in the case. I removed the secondary drive from the MX-1 housing, and mounted it inside the TiVo. I replaced the all-in-one SATA cable in the Tivo with an ordinary SATA power cable, and plugged one of the adapters into the internal (now secondary) drive I plugged the other into the internal SATA header. Outside the TiVo, I took a short eSATA jumper and ran it from the embedded eSATA connector to the new adapter which feeds the internal drive. Finally, I mounted the primary drive in the MX-1 housing and plugged it into the remaining eSATA adapter, being fed from the internal SATA port of the S3.

Your post makes me wonder if I could eliminate the internal drive altogether and plug a port multiplier external case into the S3. Hmmm.